1. Field of the Disclosure
The present disclosure relates to a method and apparatus for processing a Circuit-Switched (CS) call by a User Equipment (UE) that is camped on a manually selected Closed Subscriber Group (CSG) cell.
2. Description of the Related Art
The Third (3rd) Generation Partnership Project (3GPP) defines a Closed Subscriber Group (CSG), which identifies subscribers of a service provider that are permitted to access a cell of a Public Land Mobile Network (PLMN), but which may have restricted access. More specifically, a CSG cell is accessible by members of the CSG, using a CSG Identity (CSG ID).
In a manual mode of CSG selection, a user of the UE selects a CSG cell. Specifically, the UE scans for available CSG cells, from which the user manually selects a CSG cell. The UE behavior may be differentiated based on whether the selected CSG cell belongs to a Registered PLMN (RPLMN) or to a different PLMN.
If the PLMN of the selected CSG cell is different than the RPLMN, then the UE saves the “current PLMN selection mode” and a duplicate value of the RPLMN into a non-volatile memory. Further, upon successful registration on the selected CSG cell, the RPLMN is not updated with that of the selected PLMN.
For example, when the UE is camped on the selected CSG cell, which belongs to a PLMN that is different than the RPLMN, and a CS call is initiated by a user the UE, the UE sends an Extended Service Request (ESR) to the PLMN of the manually selected CSG cell. However, because the manually selected PLMN is different from the RPLMN, the PLMN of the manually selected CSG cell may send a Redirection Request to the UE. The Redirection Request requests the UE to camp on a 3G/2G cell associated with the PLMN of the manually selected CSG cell or another PLMN in the network.
Based on the redirection request, the UE moves out of the currently camped CSG cell and initiates a cell search procedure for the 3G/2G cell on the PLMN associated with the manually selected CSG cell or the another PLMN in the network.
In current systems, when the UE moves out of manually camped CSG Cell (or when the UE loses the coverage of the user selected CSG cell), the UE changes the PLMN selection mode back to the PLMN selection mode saved prior to the manual CSG selection, and attempts recovery with the saved duplicate value of RPLMN. Hence, the CS call initiated by the user may not be processed by the UE, when the UE attempts recovery with the saved duplicate value of RPLMN (e.g., when UE moves out of currently camped CSG cell).
If the CS call is processed at the UE by camping on the 3G/2G cell of the same PLMN or a different PLMN, the UE returns to the stored duplicate value of the RPLMN, upon the termination of the CS call.
In the current systems, after the processing of the CS call, the user may have to manually select the CSG cell in order to camp on and re-register with the previously selected CSG cell. Accordingly, there is need for an easier method to camp on and re-register with the manually selected CSG cell.